Teenage survivors of South Korea's worst maritime disaster in 20 years, many wearing yellow bracelets, walked out of classrooms on Tuesday and marched on parliament to demand enabling legislation for a inquiry into the more than 300 deaths.

More than half of the 75 children rescued from the ferry Sewol that capsized and sank on April 16 joined growing public calls for parliament to pass a special bill for an independent inquiry sought by victims' families. More than 3.5 million signatures have been collected to demand its passage.

“The entire nation saw it on April 16. We ask that the truth behind the unfair deaths our friends suffered be told,” said a bespectacled boy taking part, who asked not to be identified.

“We don't know much about the law, but if we don't do this there is nothing we can do, so we ask that our wish is met.”

Of the 476 passengers and crew, 339 were children and teachers from Danwon Highschool on the outskirts of Seoul. Only 172 people were rescued and the rest are presumed to have drowned.

The children passed though the school's stone gates and down a boulevard, mostly in silence.

Many wore the bracelets emblazoned with “Remember 0416” or sashes and kerchiefs made out of yellow pieces of cloth - the color chosen to express dissatisfaction with the authorities' handling of the disaster.

“Our children are marching with their pure hearts to console parents of their friends and ask to find the truth of the disaster,” said Oh Ji-yeon, the father of one survivor.

The children made their way to a small park where 15 relatives of victims were undertaking the second day of a hunger strike to press for the bill. Marchers set up displays of yellow paper boats to draw attention to the strikers.

Boxes of signatures

Nearby, organizers set up neat rows of boxes, covered in yellow paper, each containing some of the 3.5 million signatures backing the petition to parliament. Several dozen adults had earlier marched to the site carrying yellow umbrellas.

The Sewol's 15 surviving crew members, including the captain, are on trial on charges ranging from homicide to negligence. Security forces have been engaged in a manhunt for more than two months for the head of the family that owns the holding company of the ferry operator.

Families of the victims and survivors say too little is being done to establish the truth about what led to the disaster on a routine journey to the holiday island of Jeju.

The special law demanded by the petitioners would ensure their participation in an independent probe into the sinking. The families have demanded the right to name half the experts from the independent team to pursue the inquiry.

Parliament has agreed to consider the bill, but is split on legal grounds over whether to grant the group investigative authority. Investigators have established that the Sewol was overloaded and traveling too fast on a turn when it sank.

President Park Geun-hye's government has come under heavy criticism for its handling of the disaster and the sluggish rescue operation. Her prime minister resigned but was reinstated after two failed attempts to find a replacement.